This invention relates generally to land based gas turbine power plants, and specifically to a tubular connector used to radially connect axially extending cooling tubes in a gas turbine rotor cooling circuit.
A steam cooling circuit for a gas turbine rotor is disclosed in commonly owned U.S. Pat. No. 5,593,274. Briefly, cooling steam is supplied via a tube concentric to the rotor and then via radial passages to axially extending tubes (parallel to but radially outwardly of the rotor axis) which supply cooling steam to the buckets of one or more of the turbine stages. A similar return path is employed to remove the steam. Because of the rotating environment of the turbine rotor assembly and the centrifugal forces generated thereby, and because of thermal expansion of the various components, any radially oriented coolant tubes must be designed to accommodate relative axial and radial shifting movements where the radial tubes interface at opposite ends with the axial tube fittings.
This invention relates to a tube having coupling profiles at opposite ends which are particularly advantageous in the context of radial connecting tubes in a rotating environment. Specifically, the tubes to be coupled are substantially parallel but radially offset relative to the rotor axis. The fittings which mate with the tube of this invention, however, are in axial alignment with the radial tube. For purposes of this discussion, and unless otherwise explained, references to radial vs. axial or to radially xe2x80x9couterxe2x80x9d or radially xe2x80x9cinner,xe2x80x9d take into account the orientation of the tube as installed in a turbine rotor assembly. References to the xe2x80x9cupperxe2x80x9d or xe2x80x9clowerxe2x80x9d ends of the tube correspond to radially outer and inner ends of the tube, respectively, relative to the rotor axis. Reference to a xe2x80x9cradial flangexe2x80x9d on the tube, however, is made with respect to the longitudinal center axis of the tube itself.
In one exemplary embodiment, the radially outer or upper end of the tube has an enlarged radial flange (but with a constant tube ID) formed with a tapered edge, the taper extending inwardly toward the longitudinal center axis of the tube in an upward or radially outer direction. This taper is part spherical in shape so that engagement with a flat conical seat formed on an axially aligned end of an elbow component attached to the radially outer axial cooling tube is substantially tangential. As a result, the radially outer or upper tube end is able to xe2x80x9crollxe2x80x9d in the seat in virtually any direction, thus accommodating relative shifting movement between the radially oriented tube and the axial tubes to which it is coupled while, at the same time resisting any radially outward movement which might otherwise occur due to centrifugal forces generated by rotation of the rotor.
The radially inner or lower end of the tube is formed as a xe2x80x9chalf-spoolie,xe2x80x9d i.e., the lower free end of the tube is expanded to form a part toroid, formed by a part spherical surface. In other words, an annular groove is formed about the tube end, while the thickness of the tube wall remains substantially constant. This end of the tube is slidably received in a radially extending cylindrical bushing formed in the radially inner, axially extending tube. This arrangement results in tangential line contact at the interface of the tube and a cylindrical ID of the bushing. There is no restraint on any radial movement of the tube at this end, however, (i.e., other than friction) so that the tube can thermally expand in a radially inner direction relative to the rotor axis, even though the tube is constrained against thermal growth at the radially outer end thereof.
Accordingly, in its broader aspects, the invention relates to a tubular connector adapted to extend between two tubular components comprising a tubular body having an internal diameter, a first free end including an annular radial flange having a tapered surface adapted to engage a complementary seating surface on a first of the two tubular components, the internal diameter remaining constant through the first free end; and a second free end having an annular bulbous shape adapted to seat within a cylindrical end of a second of the two tubular components.